A dust transaction in cryptocurrency refers to a very small amount of tokens or coins that is so small it may be uneconomical to spend due to transaction fees exceeding the value of the amount. 'Dust attacks' involve sending tiny amounts to wallets to track and de-anonymize their owners.
Example
“The wallet received a dust transaction of 0.00000546 BTC from an unknown sender, which the user recognized as a potential dust attack intended to track their spending patterns.”